Apparatus for removing smoke and odors from domestic cooking vapors



June 14, 1960 D. w. SCOFIELD APPARATUS FOR REMOVING SMOKE AND ODORS FROM DOMESTIC COOKING VAPORS 2 Sheets-Sheet 1 Filed May 1, 1957 INVENTOR. DOD/7L0 LU. JCOF/fLD United States Patent REMOVING SMOKE AND DOMESTIC COOKING VA- APPARATUS FOR ODORS FROM PORS Donald W. Scofield,

Corporation, sylvania Glenside, Pa., assignor to Philco Philadelphia, Pa., a corporation of Penn- The invention hereinafter described and claimed has to do with improvements in heat treatment and particularly in catalytic treatment. While the concepts of the invention are of broader applicability they are of particular utility in the removal of objectionable vaporborne smoke and odors such as those which commonly emanate from the ovens of domestic cooking ranges. Heat treatment and particularly catalytic treatment has been employed for abating the nuisance caused by such smoke and odors, and one form of apparatus for such purposes has been disclosed in the applicants co-pending application Serial No. 460,863, filed October 7, 1954-, now Patent No. 2,862,095, and assigned to the assignee of the present invention. The present invention provides new and improved apparatus for treating the smoke and odors from a cooking range, or various other gases or fluids. The present disclosure is a continuation-inpart of the applicant's co-pending application Serial No. 467,726, filed November 9, 1954, now abandoned, and assigned to the assignee of the present invention.

The invention provides a heating wire or the like with improved means for the support thereof, whereby it is capable of meeting the exacting requirements, imposed thereon, in a highly satisfactory manner. More specifically it provides catalytic treatment apparatus which has and maintains, in extended use, maximum contact with a flow of gases or other fluids, while allowing the application of minimum resistance to the flow.

The desirability of such apparatus has been known for a long time but the object has not been achieved in previous constructions. It has occurred to me that this want can be filled by a heater element, preferably a fiat coil of metallic wire, supported in certain characteristic ways to span the inside of a duct; and it is a particular 'object of my invention to provide such forms and sup- A further object of the invention is to provide an elongated, convoluted, electrical heating and catalyzing element, the convolutions of which have such strength :and support that they do not tend to sag or arch when heated, whereby they avoid mutual contacting and shortcircuiting and other similar irregularities.

Still another object of the invention is to provide a heating and/or catalyzing coil and support construction which allows the coil when heated to creep over a small =distance longitudinally of the wire portions of the coil, while protecting it from creep or distortion laterally of :said portions.

In the drawing appended hereto:

Figure 1 is an elevation of a catalytic treatment chamber constructed in accordance with the invention and partly broken away to show inner portions thereof.

Figure 2 is a plan view of the chamber.

Figure 3 is an end view of one of the catalytic elements removed from the chamber.

Figure 4 is a sectional view of a portion of such a catalytic element.

Figure 5 is a fragmentary, chamber.

Figure 6 is an elevation of a modified catalytic treatment chamber constructed in accordance with the invention, with portions broken away.

Figure 7 is a plan view of the and Figure 8 is an enlarged, schematic view of a detail of the chamber of Figure 6.

Referring first to the embodiment of Figures 1 to 5: this embodiment includes a chamber 10, open at Opposite ends 11 and 12 to form a duct for the passage of gases or the like. The chamber is here shown as constructed of substantially square side members 13 and 14 and rectangular end members 15 and 16, all fabricated of material having low or practically zero conductivity for electricity and heat. These members are shown as secured together by screws 17 to form a boxlike, open-ended chamber. The inner surfaces of the side members 13 and 14 are provided with superposed, parallel grooves 18 and the inner surfaces of the end members 15 and 16 are similarly provided with grooves 19, pairs of grooves 18 and 19 being aligned with one another to form continuous rings of grooves around the inner walls of the chamber.

Each side groove 18 receives one side 20 of a gas permeable catalytic element 21 and cooperates with the other grooves of the corresponding ring of grooves to support the said element and to space it from similarly supported elements in the other grooves. As clearly shown in Figure 2, the catalytic coil elements 21 span the chamber from wall to wall in both directions, and each turn of such a coil spans the chamber from side to side.

Each catalytic element 21, as shown in Figures 2 and 3, comprises a substantially flat, generally helically shaped coil of catalytic material, preferably comprising a metallic wire 22 which may for instance be coated, as shown in Figure 4, with a suitable catalytically active coating 23. While the wire and/or the catalyst may be of various suitable materials it has been found that wire of Nichrome (an alloy of nickel and chromium), coated with platinum black, either with or without alumina or the like as a carrier or intermediary, is satisfactory for many of the purposes indicated above.

Each coil 21 has a certain amount of flexibility to permit elongation or shortening thereof, from end to end, whereby the spacing between adjacent turns of the coil may be adjusted as desired, so long as the coil has not been installed in a frame or chamber 10 as yet. Thus each coil can be flexed so as to fit in a frame such as that shown at 10 but with side members either shorter perspective view of the chamber of Figure 6;

or longer than those shown at 13 and 14, thereby pro-' viding either closer or wider spacing between the different spans and turns of the coil. This allows a suitable adjustment of the way in which the coil structure contacts the gas to be treated in each individual application of the device. When once installed in a chamber 10, the coil 21 is prevented from further significant flexing.

The coils are subject to a certain amount of expansion and contraction, depending on their operating and nonoperating temperatures; this contraction and expansion taking place during the use of a coil, in a direction normal to the side members 13, 14 (whereas the aforementioned flexing and adjusting of the coil is performed in the manufacture of the device, in a direction parallel with said side members). Figure 2 may be considered as showing the coil 21 in hot and fully expanded condition, such that the coil extends all the way into the side grooves 18. When exposed to cooling and contraction, the coil retracts a smallarnount from the side walls of these grooves, while it is still supported by the bottom of each groove. In other words, a suitable, small amount of creep space for thecoil'is provided by the side grooves. This arrangement has been found most usefulin making sure that the different spans 'of the coil, extending across the housing, do not as a result of their heating and cooling cycles either arch or slag into positions wherein they touch one another and thereby short-circuit currents of electricity employed to heat them and to actuate the catalytic coating.

As shown in Figure 1, end portions 24 of each coil extend through apertures provided in end members IS'andv 16' or the chamber; 'and'adjacent pairs of such end portions 24are twistcdor otherwise secured together as indicated at 26, thus to conn'ect the coils in series. The terminal spans of each coil, as best shown in Figure 2, lie within or closely adjacent to the end "grooves 19, thereby safely avoiding any bypassing of the fluids to be treated around the catalytic coils and forcing all of said fluid to flow through the suitably adjusted coil-elements 21.

The ends 27 and 28 of the-series-connected elements are connected, as byconductors 29 and 30, to a suitable source of electrical energy, indicated at 31; a control switch 32 being interposed in line 30.

The assembled duct and coil means 10, 2-1 can be inserted, for instance, in a chamber such as that shown at 27 in my aforementioned application Serial No. 460,863.

In operation, elements 21 are energized, as by closing switch 32, to heat and'thus activate the catalyst 23. A temperature of approximately 700 degrees F. is. often adequate for this purpose, although under certain conditions other temperatures arepreferable. When the catalyst has reached the desired temperature thegases to be treated are introduced into. the chamber at one open end thereof and forced-through the catalytic units either by ordinary draft or by a blower, not shown, or inother known ways. As. the gases contact the catalyst, contaniinants in thegasm, such as vapor-borne smoke andodors, are oxidized. or incinerated and. thus eliminated. In. atleast some instances, this. action may contribute to theheating of the coils. The clean gas leaves the-chamber from the-oppositeopen end.

In the modification of Figures 6 to 8, a, treatment chambers;60tis formed with openends fil and 62, by stacking aplurality. of horizontal frame members 63, 64, 65, 66; on top of one another, with coils of substantially the same form as described above, inserted in and supported by, grooves 67. Each ofthesegrooves. is here formed by n bet en mat n sur a es Q a p the t d up amesyfifi, .5 tc E ch ra o pr ses a pair of end members 68, 69 andapair ofsidemembers 70, 71; these members beingintegrally formed or molded of a suitable substance, suchas a refractory ceramic material.

, Eachend; member 68, 69 may have an car 72 formed integrally, therewith and outwardly extending therefrom, withfa bolt hole 73 extendiugthrough the ear and aligned withthe corresponding bolt holes of the other frames, so that. a stack'of the frarnes can be held together by simple fastening iand support means such as bolts 74. Proper alignment of the superposed frames is further aidedby incorporating in the top surface 75 of each frame an up- Wardly projecting key structure such as'a V-shaped' ridge 76, interlocked with a matching groove 77 in the'next overlyingfrarne; uniform keys'jandj grooves being incor porated all frame members of fa unit. Desirably these keysand grooves areannular, as shown, extending practically around; the entire frame. They serve to minimize escape of fluid between stacked up frames, to reinforce each frame against thermal stresses resulting from the heatingand 'cooling-of' the treatment chamber; and to distrihutehoth :thermal and mechanical loads: imposed .on

diY' ds ali ramc mbersin the stack. by the heating; and

xnansiq of-c ils The manner in which the stack of frames 63 to 66 fur nishes support as well ascreeping space for a flatcatalytic coil 78 is best illustrated in Figure 8. Here the letter L designates the approximate length of each span 79 of the flattened coil 21, between the terminal turns 80 thereof, when the coil is at ordinary room temperature, whereas the letter B designates the maximum expansion of any span 79 when the coil is heated; the magnitude of this dimension E being slightly exaggerated in the interest of a clear diagrammatic showing. It will be notedthat a ledge 83', forming a lower'wall of each groove 67, has a width W which may be small but which is greater than the expansion or creep space E, so that the coil 78-is adequately supported both in the expanded and contracted conditions thereof.

Preferably eachspan 79 of a coil '78 has ends 80 which are bent, relative to the span, in at least fairly sharpcornered form, as shownat C. Thissharp-cornered design of the coil facilitates the 'rnaintaining of supporting and positioning action by grooves 67'of relatively narrow width W, as just described. Another advantage of this sharp-cornered design is that it aids in the manufacture of a flat coil with substantially parallel,.suitably spaced, individual spans.

I have further found it desirable to keep the coils tensioned between the ends '68, 69' of their frames (Fig. 7), while leaving them free to expand and contract between the sides '70, 71.. More particularly I prefer to keep the coils tensioned when they are thermally expanded, as well as in their relatively cool condition, thereby'safel-y counteracting any tendency of different spans or turns to contact one another and to short-circuit any" parts ofithe path for the electric current. For this purpose each frame is shown as being provided with two grooves sl formed in the: top surface, 75 and extending; from opposite poi" tions of the inside of the frame,across the rib or key 76, to the outside of the frame, thereby facilitating niechanicalanchoring as well as electrical connection ofend portions 82 of the coil 78. Evidently such end port-ions 82 can be formed, for instance, in the same way as shownat 26 in Figure 1, whereby they form'means for holding thecoil means 78 in grooves 62' of sides 70-, 71,.whi-Iea1- lowing small motions of wire turns 80 both along and across the direction of said grooves. This facilitates keeping wire spans 79' spaced apart, regardless ofthermal expansion and contraction thereof.

In both embodiments ofv the invention. described above it is possible to combine catalytic coils, shown at 78 inv Figure 6, with similarly formed and: installed, plainpreheating coils, shown at 83. Such preheatingcoilsmay in some cases be-dimensioned so. as to provide relatively narrow flow areas 84 for the flow- 85; of relatively cool, unexpanded gas, passing into the. treatment chamber. They may sometimes be operated so as to maintain relatively high temperatures at the; surface of: the coili material, inorder to obtain rapid. preheating of; the fluidand thereby to. safeguard the most efiicientoperation of. the

H catalytic apparatus; and correspondingly, such coilsmay have relatively large expansion E (Fig. 8). However, numerous modifications.- are possible in these respects.

Apparatus of the kind described. has in practice proven to, be highly advantageous, overcoming mechanical prob.- lerns; which have plagued. previous attempts to provide catalytic; equipment. The required intimate contact be.- tween flowing fluid and surface portions of the catalytic coils is provided and is maintained without-disturbance by sagging, arching, or the like, even in the-presence of unavoidable fluctuations of. temperature in the. gas,,. the coils and/or thecoil supports. In this Way,. diffic1ilties such as those caused by. short-circuitingbetween catalytic coil elements aresafely avoided,, even: where the gases or. other fluids under. treatmentare exposed to steep temperature gradients betweeninlet and outlet. of the. treat.-

- ing chambenandeyen where such fluids carry extremely The entire catalytic surface can thus be operated at narrowly selected temperatures, being safely protected from local shorting out and the like and from difiiculties caused by temperature variations along the wire of a coil.

While only two embodiments of the invention have been described, it should be understood that the details thereof are not to be construed as limitative of the invention, except insofar as set forth in the following claims.

I claim:

1. In apparatus for removing smoke and odors from domestic cooking vapors and the like: a rigid refractory frame structure, providing a passage for the vapor and having at least one pair of parallel, mutually facing grooves, formed in inner walls of said passage, said grooves being elongate in a direction parallel to said inner walls and transverse of said passage and having substantially the same depth throughout their entire length; substantially fiat coil means of metallic wire, having a surface structure catalytically active to promote removal of said smoke and odors and comprising a series of longitudinally aligned convolutions, each convolution including a pair of wire turns, so supported in said grooves as to allow slight motions of said wire turns along as well as across the direction of said grooves, each convolution also including a pair of substantially straight wire spans, between said wire turns; and a pair of wire elements, one secured to each final convolution of said coil means, said wire elements extending through said frame structure and including wire portions so secured, outside said frame structure, as to hold said coil means tensioned, in a direction parallel to the direction of said grooves, while allowing said motions, and for thereby keeping said wire spans spaced apart, regardless of thermal expansion and contraction thereof.

2. Apparatus as described in claim 1, including, as part of each of said wire turns, portions of said coil means bent in sharp-cornered manner, so that said wire turns include straight portions extending at right angles to said wire spans.

References Cited in the file of this patent UNITED STATES PATENTS 1,557,104 Thornton Oct. 13, 1925 1,671,742 Pronty May 29, 1928 2,500,501 Trumpler Mar. 14, 1950 2,731,541 Houdry Jan. 17, 1956 

1. IN APPARATUS FOR REMOVING SMOKE AND ODORS FROM DOMESTIC COOKING VAPORS AND THE LIKE: A RIGID REFRACTORY FRAME STRUCTURE, PROVIDING A PASSAGE FOR THE VAPOR AND HAVING AT LEAST ONE PAIR OF PARALLEL, MUTUALLY FACING GROOVES, FORMED IN INNER WALLS OF SAID PASSAGE, SAID GROOVES BEING ELONGATE IN A DIRECTION PARALLEL TO SAID INNER WALLS AND TRANSVERSE OF SAID PASSAGE AND HAVING SUBSTANTIALLY THE SAME DEPTH THROUGHOUT THEIR ENTIRE LENGTH, SUBSTANTIALLY FLAT COIL MEANS OF METALLIC WIRE, HAVING A SURFACE STRUCTURE CATALYTICALLY ACTIVE TO PROMOTE REMOVAL OF SAID SMOKE AND ODORS AND COMPRISING A SERIES OF LONGITUDINALLY ALIGNED CONVOLUTIONS, EACH CONVOLUTION INCLUDING A PAIR OF WIRE TURNS, SO SUPPORTED IN SAID GROOVES AS TO ALLOW SLIGHT MOTIONS OF SAID WIRE TURNS ALONG AS WELL AS ACROSS THE DIRECTION OF SAID GROOVES, EACH CONVOLUTION ALSO INCLUDING A PAIR OF SUBSTANTIALLY STRAIGHT WIRE SPANS, BETWEEN SAID WIRE TURNS, AND A PAIR OF WIRE ELEMENTS, ONE SECURED TO EACH FINAL CONVOLUTION OF SAID COIL MEANS, SAID WIRE ELEMENTS EXTENDING THROUGH SAID FRAME STRUCTURE AND INCLUDING WIRE PORTIONS SO SECURED, OUTSIDE SAID FRAME STRUCTURE, AS TO HOLD SAID COIL MEANS TENSIONED, IN A DIRECTION PARALLEL TO THE DIRECTION OF SAID GROOVES, WHILE ALLOWING SAID MOTIONS, AND FOR THEREBY KEEPING SAID WIRE SPANS SPACED APART, REGARDLESS OF THERMAL EXPANSION AND CONTRACTION THEREOF. 